The present invention generally relates to brakes, specifically relates to brakes for linear motion applications, and more specifically relates to linear motion brakes having special application to power-off situations.
The popularity of linear motors in the machine tool, semiconductor, and medical industries has been increasing as the result of their ability to move a load in a linear movement direction to a position with extreme accuracy and at very high speeds. However, problems have been encountered in stopping linearly moving loads especially in the event of a power outage. Specifically, as movement and positioning of the load is dependent upon current being supplied to the linear motor, loads carried by linear motors will move under gravitational and/or inertia forces in the event that current is interrupted to the linear motor such as the result of a power outage. This problem is also enhanced in linear motors because of the use of high performance linear bearings which minimize sliding friction.
Although marketing of linear motor packages is increasing in popularity, often the end user purchases the various components of linear motors such as linear bearings, armatures and magnet tracks or stators, and position feedback devices and arranges such components according to their particular application. Thus, linear motors have a variety of configurations.
Although linear motion brakes have been utilized in other fields such as roller coasters, attempts to provide brakes for stopping linear motion of loads driven by linear motors have not been commercially viable, possibly due to their relative small size.
Thus, a need exists for a brake for stopping linearly moving loads and especially for use with linear motors and particularly for use in stopping linearly moving loads in the event of a power outage, emergency stop, parking, or similar situation. In a preferred aspect, the linear motion brake must be adaptable for use with any configuration of a linear motor and in most preferred aspects is modular in form for attachment to the linear motor if and when braking is desired in the particular application of the linear motor.